Multiple vulnerabilities have been discovered in the Apache HTTP server:

Jonathan Peatfield reported that the "Options=IncludesNoEXEC" argument to the "AllowOverride" directive is not processed properly (CVE-2009-1195).

Sander de Boer discovered that the AJP proxy module (mod_proxy_ajp) does not correctly handle POST requests that do not contain a request body (CVE-2009-1191).

The vendor reported that the HTTP proxy module (mod_proxy_http), when being used as a reverse proxy, does not properly handle requests containing more data as stated in the "Content-Length" header (CVE-2009-1890).

Francois Guerraz discovered that mod_deflate does not abort the compression of large files even when the requesting connection is closed prematurely (CVE-2009-1891).

Impact

A local attacker could circumvent restrictions put up by the server administrator and execute arbitrary commands with the privileges of the user running the Apache server. A remote attacker could send multiple requests to a server with the AJP proxy module, possibly resulting in the disclosure of a request intended for another client, or cause a Denial of Service by sending specially crafted requests to servers running mod_proxy_http or mod_deflate.

Workaround

Remove "include", "proxy_ajp", "proxy_http" and "deflate" from APACHE2_MODULES in make.conf and rebuild Apache, or disable the aforementioned modules in the Apache configuration.